A colony of chimpanzees currently housed at Meloy Labs are being evaluated for a number of viral hepatitis studies. In addition to these studies, a number of chimpanzees have received material from AIDS patients and are currently being followed in an attempt to transmit AIDS to non-human primates. Routine weekly helper to suppressor ratios (H:S) have been carried out. As of this date, no major changes have been found (five months). We have found that chimps have a greater number of suppressor marked non-T cells than do humans (13.9 vs. 5.8 respectively). Functionally, these cells appear to be natural killer cells. H:S ratio changes have been observed in hepatitis B virus (HBV) infected chimps at times of HBV inoculation and in NANB inoculated chimps prior to peak enzyme level detection. B cell activation assays are also being studied as a marker for early AIDS detection, along with B2 microglobulin and HTLV serology.